Following infection with hepatitis B virus, the majority of individuals will clear the virus and develop antibodies to several virus components including hepatitis B surface antigen. A subset of individuals may not respond appropriately to the infection and develop chronic hepatitis B antigenemia. Chronic hepatitis B antigenemia can be associated with several apparently immunologically mediated diseases including cyroglobulinemia, systemic necrotizing vasculitis, glomerulonephritis and chronic aggressive hepatitis. The ability to evaluate human immune response to hepatitis B surface antigen (HBsAg) should provide insights to a number of apparently immunologically mediated diseases. By the use of an enzyme-linked immunosorbent assay (ELISA) technique, it is feasible to measure antibody to HBsAg (anti-HBs) produced in vitro. In peripheral blood mononuclear cells (PBMC) from individuals immunized with HBsAg vaccine, low doses of HBsAg in vitro stimulate antigen-induced antigen specific antibody production. This antigen-induced specific antibody response is dependent on the presence of monocytes, antigen specific T cells and B cells in the peripheral blood compartment. This system provides an approach to evaluating antigen specific immunity in disease states characterized by an abnormal host immune response to HBsAg. Using this system, I propose to evaluate HBsAg specific immunity in both peripheral blood T cell and B cell populations in patients with asymptomatic HBsAg antigenemia and chronic hepatitis associated with antigenemia. The studies will be performed by both 1) immunization and subsequent cross stimulation in vitro with noncross-reacting antigens such as keyhole limpet hemacyanin and/or tetanus toxoid, and 2) allogenic coculture studies using HBsAg vaccine recipients with established immunity to HBsAg. In addition, using existing T cell cloning techniques, I propose to grow and clone lymphocytes from liver tissue samples. The ability to clone cells from the liver makes it feasible to evaluate antigen specific (HBsAg) immune responses in lymphocyte cells from disease associated sites (liver) in chronic hepatitis. The cloned cells will be evaluated for a number of HBsAg specific immune responses. The ability to evaluate antigen specific immunoregulatory questions in cells from disease-associated sites should provide new insights into the abnormal human immune response to HBsAg.